add s3cmd installation step in Dockerfile (Jewel, Ubuntu 16.04) (#612)
add s3cmd installation step in Dockerfile (Jewel, Ubuntu 16.04) (#612)

* add s3cmd installation step in Dockerfile

cdxvirt/ceph-docker,mkkie/ceph-docker,mkkie/ceph-docker,ceph/ceph-docker,cdxvirt/ceph-docker,rootfs/ceph-docker,osixia/ceph-docker,osixia/ceph-docker,rootfs/ceph-docker,osixia/ceph-docker,JrCs/ceph-docker,ceph/ceph-docker,JrCs/ceph-docker,JrCs/ceph-docker